Process for applying metal lubricants



Patented Sept. 5, 1933 UNITED STATES PATENT OFFICE PROCESS FOR APPLYINGMETAL LUBRICANTS No Drawing. Application May 13, 1929 Serial No. 362,867

15 Claims.

My invention relates to the art of applying metal lubricants to thesurface of metals to be used in drawing operations and more particularlyin the drawing of fine wire.

tion of lubricating coatings for all types of drawing operations, Ishall describe my invention in reference to the drawing of fine wirewhere many of the advantages and benefits resulting from the inventionare more, particularly utilized. I shall endeavor throughout thespecification to set forth the broad principles involved, givingspecific examples by way of illustration and freely stating what Ibelieve to be the facts in the belief that the information thus givenwill best acquaint those skilled in the art with the invention in itsbroadest aspect, but I realize that differences of opinion may occur andI do not wish to limit 00 myself to the theories or opinions advanced.

uses as its raw material hot rolled steel rods'of suitable size andweight. The scale, formed on the rods during the hot rolling operation,is usually removed therefrom by immersing them in 5 a pickling solutionof sulphuric acid or other suitable material. Before the first drawingoperation the rods are given a treatment of lime or other suitablesubstance which will form a surface layer upon the metal and act as alubricant between the die and the surface of the rod. Low

carbon steel wires of comparatively large diameter are usually drawn drywithout the aid of further lubrication. After the first drawing the wireis annealed, coated with a lubricant as before, and again drawn. Thus,by successive drawing operations the metal is reduced in diameter untila wire of about 21 gauge. is reached.

This may be said to be the boundary between coarse and fine wire,drawing operations upon 40 wire finer than this generally requiringbetter lubrication than that previously employed.

In order to provide a better lubricant it has been customary in theprior art to develop a layer of copper upon the surface of the wire toact as a lubricant as does the lime in the coarser operations.Subsequent drawing operations have also usually been carried out in asoap solution or similar bath to further facilitate the passing of thewire through the dies. In producing the copper coating the wire has beenfirst annealed in some suitable manner and then immersed in a sulphuricacid or other cleaning solution. The wire is then washed in water andimmersed in a coating bath. The action of this bath has been highlyerratic. The formulae have been. developed While the process isapplicable to the produc- In the manufacture of fine wire the wire millalmost completely through experience and little has been known orunderstood of the exact functions of the different components of thebath. Because of this and the complexity of the bath, when the latterfails to function properly it is generally necessary to discard the oldbath and prepare a new one. The preparation of .the bath has beensurrounded by superstitution and secrecy with the resulting inefficiencyand excessive loss of reagents due to frequent changes .of the bathcontaining unused and expensive reagents. It was necessary to dump thebath about every six to eight hours discarding all of the reagentstherein and the labor of compound ing them. It has been prepared by ruleof thumb methods and its action has been little understood. For example,one of the best of such baths is prepared in the following manner: Pigtin is flaked and added to a solution of copper sulphate and the mixturetreated with steam. The tin replaces the copper to form stannicsulphate, the copper being precipitated. The stannic sulphate solutionforms one of the reagents of the bath. Another reagent is formed bytreating copper sulphate with steam. A third reagent is formed byfermenting rye flour. The fourth and final reagent is diluted sulphuricacid. These four reagents are mixed in varying proportions, according tothe individual operator to form the coating bath. After the wire hasbeen immersed in this bath for a suitable length of time it is withdrawnand washed in water. After the coating operation the wire is many timesplaced in vats containing water and rye flour or other reagents where itis permitted to stand for from two hours to two days before being drawn.

Operations involving the drawing of fine wire have, prior to this time,almost universally employed diamond dies for the purpose. Othermaterials such as alloys of tungsten carbide have been advocated byvarious manufacturers but none of these have been found satisfactory forthe purpose. It will be seen that because of the excessive cost of thesesmaller dies it is highly desirable that a perfect lubricating coatingbe obtained upon the surface of the wire which will prevent the steel ofthe wire, during successive drawing operations, from coming in contactwith the dies. The processes of the prior art.have failed to do this,the coating produced, at least partially breaking down before the wirehas passed through the fourth die.

One of the principal objects, therefore, of my invention is theprovision of a process for applying coatings of metallic lubricants uponthe surface of metals to be acted upon. in. drawing operations.

I have also aimed to provide a method of applying metal lubricants inwhich the bath may be easily, uniformly,'and accurately prepared.

A still further object or" my invention is the provision of a coatingbath requiring no experienced help in mixing the solutions or treatingthe metal.

Another object of the invention is the provision of a process in whichthe solutions employed have little or no odor.

I have also aimed to provide a process for applying metal lubricants of,sufficient adherence and durability to permit the use of alloy diesinstead of the customary diamond dies.

A 'still further and important object of the invention is to provide ahighly simplified and economical means for applying a metal lubricant toarticles to be drawn.

Other objects and attendant advantages will become apparent to thoseskilled in the art as the description proceeds.

After heavy wire rodding has been drawn to about 21 gauge by the usualmethod and annealed I subject the wire to a novel and simplifiedtreatsolving ment whereby a highly improved metal coating is producedupon the surface thereof. Instead of cleaning in the usual five percentsulphuric acid solution I prefer to employ a solution of about sevenpercent hydrochloric acid. The concentration of acid may, however, bevaried within wide limits and I do not wish to restrict myself to anyspecific concentration. The sulphuric acid bath of. the prior art may beused for cleaning but it is messy and I prefer to use the hydrochloricacid bath whereby the subsequent washing step is eliminated, thehydrochloric acid being carried over into the following bath to providea continuing supply of acid to the subsequent bath. It will. also beseen that under certain circumstances other acids may be used inappropriate concentration, the acid depending upon its ability to cleanthe metal and upon the chemical composition of subsequent reagentspresently to be described. The method of cleaning is not an essentialpart of the process, the only requirement being that the wire be cleanedby some appropriate means. The wire after being washed in thehydrochloric acid solution as described above, is immersed for about aminute directly in a treating solution made by diswhite arsenic orarsenous oxide in hydrochloric acid. The acid may be diluted if i.desired and an excess of arsenic should be added,

-. bination of these salts than with the copper salt alone, due, nodoubt, to the repressing action of common ion. The specific gravity ofthe bath is about ties. The wire need only remain in this bath for aboutthree minutes and is then removed and washed when it is ready for subseuuent drawing operations.

Iit will be found that very little care is required in the preparationof solutions, the arsenic bath being effective so long as an excess ofacid and arsenic remain in the solution. I have found masses that thebath lasts indefinitely and that in operation the only attention itrequires is periodic additions of arsenic and acid. While, no doubt, thebath acquires certain impurities from the metal passing through it,these do not appear to ever reach sumcient concentration to interferewith the normal functioning of the bath. The concentration of the copperbath does not appear to be important so long as it retains itsblue-green color, in other words, so long as it retains appreciablequantities of copper ions. The bath never needs to be dumped or changedif additions of blue stone are made from time to time to maintain theconcentration thereof. While I do not profess to know the theory of thereactions taking place in the process I am led to believe that thearsenic deposit acts as an inhibitor of the subsequent reaction betweenthe iron' and the copper salts. The copper coating is believed to beformed by the replacement of copper in the copper salt by the iron ofthe metal, the copper precipitating upon the wire. If this reactiontakes place rapidly the copper will be rapidly liberated and form uponthe wire in comparatively loose powder. This deposit will be insecurelyheld to the wire. If, however, the rate at which this copper isliberated from its salt is materially decreased it will precipitate uponthe wire in very fine crystals, whereby a highly adherent coating willbe produced. The arsenic is believed to reduce the rate of this reactionand consequently increase the tenacity with which the surface film ofcopper is held. Its function is thought to be that of an inhibitor sinceonly minute quantities are consumed in the process. It is also believedthat any compound of arsenic may be usedfor this purpose which willfurnish substantial quantities of arsenic ions. This means that anywater soluble dissociated compound of arsenic may be used.-

According to this theory suflicient arsenic is absorbed by the wire andcarried through the washing bath into the copper bath to effectivelyretard the rate at which the copper is deposited. While I have mentionedonly arsenic, soluble salts of other metals, such as antimony, bismuthor lead, may be employed though I have found arsenic to be superiorthereto for the purpose.

It will be seen that other compounds of copper than the sulphate may beemployed. fact,

any copper compound may be used which is ca pable of yielding copperions in solution. I have found the ammoniacal salts of copper to besatis factory. The soluble salt of any metal in which the iron willreplace the metal of the salt and cause it to be thrown out of solutionmay be used such as gold, silver, or lead salts.

First among the numerous benefits derived from my improved process isthe fact that wire carrying these coatings may be carried, in a soapsolution, through an indeterminate number of dies without breaking thecopper coating thereon. In a single operation I have carried wire socoated through nine to eleven dies increasing the length of the wire byeight times and reducing the wire from 21 gauge to 33 gauge withoutbreaking this surface film. The resulting wire retains a distinctlycopper color and upon examination has been found to have an unbrokencontinuous surface layer. When we contrast this with the fact that wirecoated by the best method of the prior art is scarcely capable of beingdrawn through three dies without a break in this surface lubricatinglayer, the utility of my invention will be apparent. It will be seenthat when the wire is coated with the metal lubricant according to myprocess the dies through which it is subsequently passed never come indirect surface contact with the steel wire. This results in a muchlonger die lire; for example, diamond dies drawing wire coated by theprocesses of the prior art from 21 to 33 gauge, will produce less than1000 pounds of wire per finishing die. Artificial dies can notsatisfactorily be used. On the other hand, diamond dies drawingsubstantially the same wire, treated by my process, to 33 gauge Wirewill produce about 2000 pounds of wire per finishing die. Alloy dies maybe used very satisfactorily with my invention and produce severalthousand pounds of wire per finishing die. Because of the very high costof 'these dies the increased production results in a very substantialsaving, since a greatly increased quantity of wire is produced from eachdie and alloy dies of lower cost may be employed. I have found that bythe use of my improved process the cost of drawing dies is reduced toabout one-sixth of that where the old process is used.

Another very important advantage obtained from my improved process isthe reduction in labor cost, plant space and plant equipment. Whencoating baths are prepared by the old method a number of mixing tanks,storage tanks and heating tanks are required to prepare the solutions.These are entirely eliminated by my process since the solutions areprepared directly in the treating tanks. Experienced workmen of somedegree of skill are required to make the treatment according to the oldprocess since much is left to the discretion of the workman. Thetreatment may be carried out by unskilled workmen where my process isemployed because the baths are of indefinite duration and the operationsof the workmen are purely mechanical.

another source of economy in my improved process is the elimination ofthe use of tin. Under the old process the cost of tin was about halt thecost of the materials used in treating the w re. This cost is entirelyeliminated by my process. While a small amount of arsenic is employed myprocess which. was not employed in the prior the cost oi this materialis negligible in comparison. with the cost of tin.

will he that the labor incident to the preparation oi": the coatingsolutions of the prior art is entirely eliminated. was necessary todalre the tin, prepare the tin sulphate, ferment the flour coat: thernirirture oi reagents. r any process the solutions are prepared in thecold and dissolved in the treating tanks the ocess being practicallyinstantane-= ens, wiser by solutions be prepared with g the process.

ti'iough of less importance, the solutions used in my in" practicallyodorless. The as prior art, due to the fermented flour, havedisagreeable odor, at times being almost un which clings to the workmenusing the causing discomfort and embarrassnient.

i /"den wire is coated process it is ready to be drawn immediately as aresult of which the coating and drawing operations may be continucue formass production. I have thus eliminated the wide varieties of treatmentsformerly given to the wire between the coating and the drawingoperations in the attempt to produce a more adherent and compact ofcopper or other metal upon the wire to protect the dies through which itis to pass.

While I have thus described a specific euibodiment of my invention I am.aware that numerous changes may be made therein without departingessentially from the spirit of the invention or the scope of theappended claims, in which- I claim:

i. The process of applying a metal lubricant to the surface of metal tobe drawn comprising treating the metal with a solution containing anarsenic ion, and treating the metal with a second solution containingthe ion of a metal. capable of precipitating upon the surface of themetal to be drawn, to form. a lubricating coating thereon.

2. The process of applying metal lubricants to the surface of metal tobe drarm comprising cleaning the metal, treating the ferrous metal witha solution containing an arsenic ion, washing the metal, and treatingthe metal with a solution containing the ion of a metal capable oi beingprecipitated upon the surface of the metal, to be drawn to form acoating of improved lubricating properties.

3. The process of applying metal lubricants to the surface of ferrouswire to be drawn comprising cleaning the ferrous wire in a solution ofhydrochloric acid, treating the ferrous wire with a solution containinga substantial concentration of chloride ions and an arsenic ion, washingthe ferrous wire, and treating the ferrous wire with a solutioncontaining ions of a metal softer than the metal to be drawn and capableof being replaced in solution by the iron of the ferrous wire, wherebythe ions are precipitated upon the surface oi the ferrous wire to form acoating of improved lubricating properties.

4. The process of applying metal lubricants to the surface of ferrousmetal to be drawn comprising cleaning the ferrous metal, treating theferrous metal with a solution containing arsenic ions, washing theferrous metal, and treating the ferrous metal with a solution containingions of a metal softer than the metal to be drawn and of the ferrousmetal whereby t" ns pare cipitated upon the suriace oi the .:cus metal.to form a coating of improved lubricatinF properties.

5. The process oi? applying metal lubricants to the surface of ferrousto be drawn comprising cleaning the ferrous wire in an acid solution.treating the famous with. a solution con taining arsenic ions, washingthe "circus wire, and treating the ferrous wire with solution containingions of a metal capable of being replaced in solution by the iron of theferrous wire to form a coating or" improved lubricating prop erties.

6. The process of lubricutts to the surface of ferrous wire to d twncor; 1d

of hydrochloric acid, treating the ferrous wire with a solution preparedby dissolving white arsenic in hydrochloric acid, washing the ferrouswire with water, and treating the ferrous wire with a water solutioncontaining ions of a metal which is softer than the ferrous wire andcapable of being replaced in solution by the iron of the ferrous wirewhereby the ions are precipitated upon the surface of the ferrous wireto form a coating of improved lubricating properties.

8. The process of applying metal lubricants to the surface of ferrousmetal to be drawn comprising cleaning the ferrous metal in an acidsolution, treating the ferrous metal with a solution containing thenegative ion of the cleaning solution and an ion which inhibits thereplacement of copper by the iron of the ferrous metalfrom a solutioncontaining a copper ion, washing the ferrous metal, and treating theferrous metal with a solution containing ions of copper capable of beingreplaced in solution by the iron of the ferrous metal whereby copperions are precipitated upon the surface of the ferrous metal to form acoating of improved lubricating properties.

9. The process of applying metal lubricants to the surface of ferrousmetal to be drawn com- .prising cleaning the ferrous metal in a solutionof hydrochloric acid, treating the ferrous metal with a solutioncontaining a substantial concentration of chloride ions and ions whichinhibits the replacement of copper by the-iron of the ferrous metal froma solution containing a copper ion, washing the ferrous metal, andtreating the ferrous metal with a solution containing ions of coppercapable of being replaced in solution by the ferrous metal wherebycopperions are precipitated upon the surface of the ferrous metal toform a coating of improved lubricating properties.

10. The process of applying metal lubricants to the surface of ferrousmetal to be drawn, comprising cleaning the ferrous metal, treating theferrous metal with a solution containing arsenic ions, washing theferrous metal, and treating the ferrous metal with a solution containingions of copper capable of being replaced in solution by the iron of theferrous metal whereby copper is precipitated upon the surface of theferrous metal toiorm a coating of improved lubricating properties.

11. The process of applying metal lubricants to the surface of ferrousmetal to be drawn comprising cleaning the ferrous metal in a watersolution of hydrochloric acid, treating the ferrous metal with asolution prepared by dissolving white arsenic in hydrochloric acid;washing the ferrous metal with water, and treating the ferrous metalwith a solution containing ions of copper capable of being replaced insolution by the iron of the ferrous metal whereby copper is precipitatedupon the surface of the ferrous metal to form a coating of improvedlubricating properties.

12. The process of applying metal lubricants to the surface of ferrouswire to be drawn comprising cleaning the wire in a water solution ofhydrochloric acid, treating the wire with a solution prepared bydissolving white arsenic in hydrochloric acid, washing the wire, andtreating the wire with a water solution of copper sulphate whereby thecopper is replaced in its combination by the iron of the wire toprecipitate copper upon the wire to form a coating of. improvedlubricating properties.

13. The process of applying metal lubricants to the surface of metal tobe drawn comprising treating the metal to be drawn with a solutioncontaining the ion of antimony to precipitate this ion on the metal todrawn, and subsequently containing a copper ion capable of beingreplaced by the metallic constituent of the metal to be drawn, wherebythe copper ion is precipitated upoon the surface of the metal to form acoating of improved lubricating properties.

15. The process of applying metal lubricants to the surface of metal tobe drawn, comprising treating the metal to be drawn with a solutioncontaining an ion of a metal taken from the group comprising arsenic,bismuth and antimony, and subsequently treating the metal to be drawnwith 'a solution containing a copper ion capable of being replaced bythe metallic constituent of the metal to be drawn whereby the copper ionis precipitated upon the surface of the .metal to be drawn to form acoating of improved lubricating properties.

RALPH F. COW.

res

Mill

